MEMBRANA TYMPANI 



5*3 



and apertures which require notice. The anterior, and 

 larger, part of the wall bulges laterally, into the cavity (Figs. 

 209, 213), and forms a very evident elevation, termed the 

 promontory. Above the posterior part of the promontory 

 there is a depression called the fossa of the fenestra vestibuli ; 

 and at the bottom of the fossa is an oval aperture called the 

 fenestra vestibuli (Fig. 213). The long axis of the fenestra 

 is directed antero -posteriorly, and, in the macerated bone, 

 the aperture opens into the vestibular part of the labyrinth, 



Recessus 

 epitympanicus - 



Body of incus 



Short crus ; 



of incus ~ ~ 



Ligament j .'': 



" " 



w -- 



att* **>* 



' " a x' E ' 



f^p^TX. Superior ligament of malleus 



^^ - Head of malleus 



Anterior ligament 

 of malleus 



Handle of malleus 

 Tensor tympani 



Foot of stapes 



Septum tubae 

 auditiva; 

 Osseous part c 

 the auditory 

 tube 





FIG. 211. Left Membrana Tympani and Chain of Tympanic Ossicles 

 seen from the medial aspect. (Howden. ) 



but, in the recent state, it is closed by the footpiece of the 

 stapes (Fig. 209), the most medial of the auditory ossicles, 

 which is implanted in the fenestra. The pyramid, on the 

 posterior wall, is immediately posterior to the fenestra vesti- 

 buli. Above the fenestra vestibuli, in the angle formed by 

 the meeting of the roof and medial wall of the tympanum, 

 and therefore in the recessus epitympanicus, is an antero- 

 posterior ridge. It is produced by the canalis facialis 

 bulging into the tympanum (Fig. 213). The wall of the 

 canal is very thin, and allows the white facial nerve, which 

 is contained within the canal, to be readily seen. Below 

 and behind the promontory is the fossula fenestrae cochleae, 

 VOL. in 33 



